The rectangle Lympholine Rebounder has the SOFTEST bounce due to its spring loaded legs. This is the only rebounder on the market that has spring loaded legs. It was an invention that when it came out it sold like crazy. Soon after this the Cellerciser came out and triple tiered their springs and this expensive rebounder became very unpopular because the Cellerciser now had a softer bounce. The Lympholine is only for doing the Health Bounce. If jumping high the springs in the feet will bottom out and you will hear a loud noise if you jump too high. I recommend wearing shoes with the Lympholine rebounder. The round rebounders keep people centered more but the rectangle rebounder doesn't invert the ankles like the round rebounders.
The Lympholine rebounder was very popular when it was introduced but most people didn't want to pay so much for a rebounder that you can only do the Health Bounce and you can't jump high to do toning exercise. The same issue with this rebounder is the same I have with rebounding on the Lymphaciser. The Rebound Air is made for the Health Bounce, heck they invented the Health Bounce and you can jump a little outside the mat with its 88 gram springs but I still find the Needak and Cellerciser the softest and least jarring. The Rebound Air has a low coil count. The springs are wide barrel shaped.
It can be very difficult to pick out just the right rebounder without trying them first. I urge people to take the Rebounding Quiz and I will pick out a rebounder based on your answers.
Spring loaded legs. Usually springs this tiny would feel jarring but with spring loaded legs it feels totally different. These are similar in size to the cheap sporting good store size springs but these are high carbon steel and the springs don't break like due to the heavy gauge spring loaded feet. I still like the Cellerciser better with the 3 tensions in each spring.